When Babusar Pass is open you can take following route..
Islamabad - Hassan Abdal - Abbottabad - Mansehra - Balakot - Naran - Babusar Pass - Chilas - Gilgit - Hunza
if not open then you have to take KKH all the way..
Islamabad - Hassan Abdal - Abbottabad - Mansehra - Battagram - Besham - Dasu - Chilas - Gilgit - Hunza